New-Found Planet Could Have A Climate Just Like Earth

This artist's impression
shows HD40307g in the foreground, with its host star HD40307 and
two other planets in the system.University
of Hertfordshire

Researchers have discovered a super-Earth planet circling a star
at a distance that would allow that planet to support life.

The planet, which is at least seven times more massive than
Earth, is actually one of six planets that orbits around a star
called HD 40307, which is 42 light-years away from
Earth (a light year is the distance that light
travels in one year, which is about 6 trillion miles).

Scientists discovered three planets that closely orbit
HD 40307 in 2008. A
reanalysis of the data found three new planets, all much larger
than Earth, that also orbit the host star.

The
study[pdf], led by Mikko Tuomi from the
University of Hertfordshire and Guillem Anglada-Escude from the
University of Goettingen, was announced on Wednesday Nov. 8,
and will be published in a future issue of the journal
Astronomy & Astrophysics.

Five of the planets are too close to the star to support
water and therefore could not sustain life. But one planet,
called HD 40307-g, orbits in the star's "habitable
zone." Essentially, the distance from its star is just
right to support life — it isn't too hot that liquid water
would boil away, and the exoplanet receives enough
energy from its star that its climate and atmosphere could be
similar to Earth.

"The star HD 40307, is a perfectly quiet old dwarf star, so there
is no reason why such a planet could not sustain an Earth-like
climate," Guillem Anglada-Escude
said in a statement.

Astronomers haven't made any conclusions about whether the planet
is rocky or gassy, partly because "no such mid-range planet
exists in our own solar system," writes
the Los Angeles Times' Amina Khan. But researchers do think
the planet rotates on its own axis as it orbits around the
star, creating a daytime and night-time effect that
would simulate the environment on Earth.